Prior applications of the same inventor have dealt with a fiber-reinforced composite ring for the controlled release of at least one bioactive agent incorporated in a biocompatible matrix reinforced with absorbable/biodegradable fibers capable of providing the mechanical properties needed for inserting and maintaining the ring in a body cavity for a desired period of time. Such ring system can be used for the intravaginal, intraperitoneal, and subcutaneous delivery of at least one bioactive agent, including those used as contraceptives.
U.S. application Ser. No. 10/860,677 discloses a controlled drug release device comprising a partially or fully absorbable, fiber-reinforced composite ring system comprising an absorbable or non-absorbable matrix, an absorbable, reinforcing fibrous construct and an absorbable coating to provide three modes of controlling the release of bioactive agents and one mode for modulating the mechanical property of the ring in a body cavity during device functional use. For partially absorbable ring systems, the drug release is dependent initially on the diffusion rate of the drug through the matrix and the absorbable coating. As the latter degrades with time, the diffusion through the matrix prevails. Meanwhile, as the absorbable fibrous reinforcing construct undergoes degradation with time, the mechanical strength of the composite ring decreases to provide the desired mechanical strength retention profile. For a fully absorbable composite ring system, the degradation of the matrix offers an additional mode of controlling the release profile as compared with the partially absorbable counterpart. In effect, the invention of U.S. application Ser. No. 10/860,677 deals with a fiber-reinforced composite ring system for the controlled release of at least one bioactive agent comprising a biocompatible matrix reinforced with an absorbable/biodegradable fibrous construct capable of providing the mechanical properties needed for inserting and maintaining said ring in a body cavity for the desired period of time, and wherein the absorbable/biodegradable reinforcing fibers are made primarily from one or more cyclic monomer(s) including glycolide, l-lactide, ε-caprolactone, p-dioxanone, and trimethylene carbonate.
For the partially absorbable/biodegradable composite ring controlled drug delivery system of U.S. Application No. 60/482,898, the fiber-reinforced composite ring deals with the controlled release of at least one bioactive agent and comprises a biocompatible matrix reinforced with absorbable/biodegradable fibers capable of providing the mechanical properties needed for inserting and maintaining said ring in a body cavity for the desired period of time, wherein the reinforcing fibers are absorbable/biodegradable and the matrix is non-absorbable/non-biodegradable, wherein the non-absorbable matrix comprising a methacrylate polymer derived from at least one alkyl methacrylate monomer, and wherein the methacrylate polymer is derived from one or more alkyl methacrylate monomer(s) and N-vinyl pyrrolidone. Alternatively, the matrix may comprise a cyclodextrin or cyclodextrin derivative.
Obviously, the partially absorbable/biodegradable composite ring controlled drug delivery system of U.S. application Ser. No. 10/860,677 did not fully address the use of matrices such as silicones and polyether urethanes, which are cited in the prior art as safe carriers of many bioactive agents.
Accordingly, a CIP for U.S. application Ser. No. 10/935,808 was filed on Sep. 8, 2004, and dealt with a partially absorbable, fiber-reinforced composite for the controlled delivery of at least one bioactive agent comprising an absorbable fiber construct capable of providing time-dependent mechanical properties of a biostable elastomeric copolymeric matrix containing an absorbable microparticulate ion-exchanging polymer to modulate the release of said bioactive agent for the desired period of time at a specific biological site, wherein (1) the absorbable reinforcing fibers are formed from at least one cyclic monomer selected from the group consisting of glycolide, l-lactide, ε-caprolactone, p-dioxanone, trimethylene carbonate, and a morpholine-2,5-dione; and (2) the biostable matrix is made of a polyether urethane elastomer or a silicone elastomer, such as copolymer polysiloxane, comprising dimethyl siloxane sequences, which can be made of at least one of the Silastic® family of silicone elastomers.
Obviously, the previous applications and related teachings did not disclose (1) the use of a non-absorbable reinforcing construct in the composite ring; (2) a novel cross-sectional geometry of the ring and associated clinical benefits in terms of ease of placement and minimized vaginal tissue trauma; (3) use of a novel feature entailing the presence of a mesh encircled by the composite ring, wherein such mesh can be used as a spermiostatic net in a contraceptive device and/or a depot for the release of bioactive agents including antimicrobials and antivirals; and (4) a ring applicator that can be used as needed by the patient without physician intervention.